Panasonic GX1 Exposure

Saturation & Hue Accuracy
Fairly accurate saturation levels over most of the spectrum. Some issues with hue accuracy, primarily in orange through yellows.

Saturation. The Panasonic GX1 produced fairly accurate saturation levels at default settings. The camera pushes dark red, and dark green very slightly, darker blues a fair bit, while slightly undersaturating light green, yellow, and cyan. Average saturation is 105.7% (only 5.7% oversaturated). That's a bit lower than the ~110% average most cameras saturate these days. Some people may feel default colors are muted, especially yellows. Most consumer digital cameras produce color that's more highly saturated (more intense) than found in the original subjects. This is simply because most people like their color a bit brighter than life.

Skin tones. Here, the Panasonic GX1 did fairly well, producing natural-looking Caucasian skin tones with a noticeable push towards pink, giving a healthy appearance. Darker skin tones had a small nudge toward orange and red, but overall results were pretty good here. Where oversaturation is most problematic is on Caucasian skin tones, as it's very easy for these "memory colors" to be seen as too bright, too pink, too yellow, etc.

Hue. The Panasonic GX1 pushed cyan toward blue, red toward orange, orange toward yellow and yellow toward green. As is often the case with Panasonic models, the yellow through orange shifts were especially apparent in the yarn of our Still Life test image. The camera's average "delta-C" color error of 6.2 for JPEGs is below average, a little worse than the G3's 5.53 score (lower scores are better). The good news is the orange-yellow shifts are significantly mitigated by shooting in RAW format and using a good-quality RAW converter. The bundled SilkyPix software as well as Adobe Camera RAW do better with hue accuracy than JPEGs produced in-camera. Click here to see a Adobe Camera RAW conversion of the same Still Life shot. Hue is "what color" the color is.

Color Modes
The Panasonic GX1 offers six preset color modes or "Photo Styles" as the company calls them. You can adjust contrast, saturation (color tone for Monochrome), sharpness, and noise reduction for any of the modes, and then save the settings as a single custom option. There are also eight Creative Control filter effects available (Expressive, Retro, High Key, Low Key, Sepia, High Dynamic, Toy Effect and Miniature Effect), however we didn't test those in the lab.

Mouse over the links above to see the effect of the Photo Style presets on our Still Life target. You can click on a link to load the full resolution image.

Saturation Adjustment
The Panasonic GX1 lets you adjust the image saturation, contrast, and sharpness in five steps each. As can be seen below, the saturation adjustment was very subtle, and worked mainly on reds. We usually argue in favor of more subtle adjustments for saturation on the cameras we test, but the Panasonic GX1 goes a bit too far in that direction; we'd like to see a wider range here (more steps), but still with the fine steps the GX1 currently offers.

The table above shows results with the default as well as the two "extreme" saturation settings. Click on any thumbnail above, then click again to see the full-sized image.

Exposure and White Balance

Indoors, incandescent lighting
Slightly warm with Auto and very warm with the Incandescent white balance setting. Good color balance with the Manual setting, but a little too cool with 2,600 Kelvin. Average positive exposure compensation required.

Indoors, under normal incandescent lighting, color balance was just slightly warm with the Auto white balance setting, though the Panasonic GX1 did much better than most cameras in this regard. (While slightly warm results with the Auto setting were quite acceptable, many users in fact may prefer a slightly warm look in situations like this, to better represent the mood of the original lighting.) Results with the Incandescent setting where much too warm for our tastes, with a strong orange-yellow cast. The Manual setting produced the most accurate results, while the 2,600 Kelvin setting which should match our lights was slightly cool with a blue cast. The Panasonic GX1 required +0.3 EV exposure compensation here, which is about average for this shot. (Our test lighting for this shot is a mixture of 60 and 100 watt household incandescent bulbs, a pretty yellow light source, but a very common one in typical home settings here in the U.S.)

Outdoors, daylight
Slightly cool colors overall, with a tendency toward high contrast under harsh lighting. About average exposure accuracy.

Outdoors, the Panasonic GX1 performed pretty well, with good though slightly cool color in the Far-field shot. Skin-tones are fairly realistic in our "Sunlit" Portrait shot, with a healthy-looking pink tint. Exposure accuracy was about average, as the camera required +0.7 EV compensation for our "Sunlit" Portrait shot to keep facial tones reasonably bright. That's average for this shot, but it led to some blown highlights while leaving some dark shadows. The default exposure was a little dim for the Far-field shot, but there are very few blown highlights, though some shadows are very dark and noisy. Default contrast is on the high side, but that's how most consumers prefer their photos.

See full set of test images with explanations
See thumbnails of all test and gallery images

Resolution
Very high resolution, 2,100 ~ 2,200 lines of strong detail.

In camera JPEGs, our laboratory resolution chart revealed sharp, distinct line patterns down to about 2,300 lines per picture height horizontally, and about 2,100 lines in the vertical direction. (Some might argue for over 2,200 lines, but aliasing artifacts begin to appear before that.) Complete extinction of the pattern didn't occur until about 3,000 to 3,200 lines horizontally and vertically. We weren't able to extract significantly more high-contrast resolution by processing the Panasonic GX1's RW2 files using Adobe Camera RAW 6.6, though complete extinction of the pattern was extended beyond 3,400 lines. ACR also showed a lot more color moiré than the camera JPEG.

Use these numbers to compare with other cameras of similar resolution, or use them to see just what higher resolution can mean in terms of potential detail.

See full set of test images with explanations
See thumbnails of all test and gallery images

Sharpness & Detail
Very good sharpness overall, though some visible edge-enhancement artifacts on high-contrast subjects. Mild to moderate noise suppression visible in the shadows even at base ISO.

Sharpness. The Panasonic GX1 captures sharp, detailed images overall, though edge enhancement artifacts are visible on high-contrast subjects such as the "halos" along the thicker branches and pin cones in the crop above left. The sharpening isn't nearly as evident on lower-contrast elements, such as the pine needles and smaller branches. Given its target market, the default sharpening applied is appropriate, as we think most users printing camera JPEGs would be pleased. And of course, you can always tweak the sharpness setting to your liking, or shoot RAW and sharpen for yourself. Edge enhancement creates the illusion of sharpness by enhancing colors and tones right at the edge of a rapid transition in color or tone.

Detail. The crop above right shows the effect of noise suppression in the form of smudging of individual strands together in the darker areas of the model's hair, as well as in areas with low local contrast. This is quite common, though, and we've certainly seen stronger noise reduction from other models. There are also some bluish color blotches, that we believe may be the result of insufficient anti-aliasing filtering, and the demosaicing problems that produces. (We also saw these with previous G series cameras, but only in the very fine, reddish detail of the mannequin's hair. This is something that we've also seen with a number of other cameras in the past, including several SLRs, so it's not unusual. Processing RAW files in a good RAW converter usually minimizes or eliminates the issue, as can be seen in the ACR converted RAW crop at right.) Noise-suppression systems in digital cameras tend to flatten-out detail in areas of subtle contrast. The effects can often be seen in shots of human hair, where the individual strands are lost and an almost "watercolor" look appears.

Intelligent Resolution
The Panasonic GX1 offers four levels of "Intelligent Resolution", which essentially sharpens fine detail and outlines, while reducing noise in areas with little or no detail (such as a cloudless sky). To see how well it works, compare the crops below at each setting.

In the table above, mousing over a link at the bottom will load the corresponding crop in the area above, and clicking on the link will load the full resolution image.

As you can see, fine detail contained in and around the lettering on the bottle has progressively stronger local sharpening applied as the setting is increased, while noise in flatter areas that would normally be emphasized with standard, global sharpening is actually reduced. Sharpening halos are however more visible at higher settings. According to Panasonic, the Extended setting is designed to produce more natural results when making large prints.

RAW vs In-Camera JPEGs
As noted above, the Panasonic GX1 produces sharp in-camera JPEGs. As is almost always the case, though, quite a bit more detail can be obtained from carefully processing RAW files than can be seen in the in-camera JPEGs, with fewer artifacts to boot. The Panasonic GX1's JPEGs are pretty good in terms of detail straight from the camera, but it's often surprising how much more detail is visible after processing in a good RAW converter. Take a look below, to see what we mean:

In the table above, mousing over a link at the bottom will load the corresponding crop in the area above, and clicking on the link will load the full resolution image.

The first crop on the left is from an in-camera Fine JPEG at default settings. The second is a RAW file converted with SilkyPix 3.1 SE (the RAW converter Panasonic bundles with their RAW-capable cameras), using default settings. The third crop is also a RAW conversion done with SilkyPix but with noise reduction and sharpening set as low as they go within the editor, and then sharpened using SilkyPix's output unsharp masking feature set to 250%, a radius of 0.3 pixels, and a threshold of 0. Adobe Camera Raw 6.6 was used for the ACR conversion at right. Default settings were used for conversion, though no sharpening was applied in ACR. The image was then sharpened in Photoshop using USM of 250% with a radius of 0.3 pixel.

As you can see, the in-camera JPEG contains pretty good fine detail. SilkyPix however had trouble with the pine needles, flattening them out, even with noise reduction turned all the way down. It's likely doing some NR under the hood which can't be disabled. The results we got using SilkyPix were a bit disappointing, but we must confess we didn't experiment with different settings for very long, so you may be able to do better. The ACR conversion extracted the most detail, but also shows more noise, especially in areas with little detail such as the sky. You can always turn up the luminance noise reduction (default of zero was used here), or process the files in your favorite noise reduction program or plugin if you find the noise objectionable. Bottom line: as is usually the case, the Panasonic DMC-GX1 rewards RAW shooters with better detail (and better color) when used with a good RAW converter.

ISO & Noise Performance
Very good detail vs noise trade-off up to ISO 400, stronger noise and noise reduction at higher ISOs.

The Panasonic Lumix DMC-GX1's images are pretty clean at ISOs 160 and 200, with only minor luminance and chrominance noise visible in the shadows, but as mentioned previously, there is already some smudging visible from slightly over-zealous default noise reduction.  The effects of noise reduction become stronger as ISO increases, and a moderate amount of detail is already lost at ISO 400, where there is more visible chroma noise as well. The effects of noise reduction are more evident at ISO 800 where there's additional blurring, though stronger chroma noise reduction has kicked-in, removing a lot of color noise including the blue botches we mentioned previously. At ISO 1,600 we see additional detail loss and stronger luminance noise, though chroma noise is still well controlled. At ISO 3,200, fine detail takes a bigger hit, with shadow areas taking on a stronger purple tint. Sharpening artifacts around noisier pixels are also much more noticeable. Noise gets quite ugly at ISO 6,400 and especially 12,800: there's very little fine detail left, strong color blotches, and the camera's noise reduction coupled with sharpening artifacts produce a peppering effect. Still, the Panasonic GX1's JPEG high ISO performance is pretty good for a Micro Four Thirds model. High ISO performance is very similar to the G3 as they share very similar if not identical sensors (RAW files are practically indistinguishable in terms of noise), but the GX1's default noise reduction is stronger, yielding smoother images.

We're of course pixel-peeping to an extraordinary extent here, since 1:1 images on an LCD screen have little to do with how those same images will appear when printed. See the Print Quality section below for our evaluation of maximum print sizes at each ISO setting.

A note about focus for this shot: We shoot this image at f/4, usually using one of three very sharp reference lenses (70mm Sigma f/2.8 macro for most cameras, 60mm f/2.8 Nikkor macro for Nikon bodies without a drive motor, and Olympus Zuiko 50mm f/2.0 for Four Thirds and Micro Four Thirds bodies). To insure that the hair detail we use for making critical judgements about camera noise processing and detail rendering is in sharp focus at the relatively wide aperture we're shooting at, the focus target at the center of the scene is on a movable stand. This lets us compensate for front- or back-focus by different camera bodies, even those that lack micro-focus adjustments. This does mean, though, that the focus target itself may appear soft or slightly out of focus for bodies that front- or back-focused with the reference lens. We know this; if you click to view the full-size image for one of these shots and notice that the focus target is fuzzy, you don't need to email and tell us. :-) The focus target position will have been adjusted to insure that the rest of the scene is focused properly.

Extremes: Sunlit, dynamic range and low light tests
Somewhat high default contrast and limited dynamic range. Very good low-light performance.

Sunlight. The Panasonic Lumix DMC-GX1 struggled a bit with the deliberately harsh lighting of this test. Contrast was a little high at its default setting, and dynamic range limited, with quite a few blown-out highlights in the mannequin's shirt and flowers and deep, somewhat noisy shadows. Although skin tones around the eyes are a bit dark at +0.7 EV exposure, we preferred it to the +1.0 EV exposure overall, because there were fewer clipped highlights. It's really the photographer's choice here as to which direction to go in. For those Panasonic GX1 owners that are going to want to just print an image with little or no tweaking, the +1.0 image would probably produce a better-looking face uncorrected. The bottom line though, is that the Panasonic GX1 had difficulty with the wide dynamic range of this shot, at least with its default settings.

Because digital cameras are more like slide film than negative film (in that they tend to have a more limited tonal range), we test them in the harshest situations to see how they handle scenes with bright highlights and dark shadows, as well as what kind of sensitivity they have in low light. The shot above is designed to mimic the very harsh, contrasty effect of direct noonday sunlight, a very tough challenge for most digital cameras. (You can read details of this test here.)

Dynamic Range Analysis
A key parameter in a digital camera is its Dynamic Range, the range of brightness that can be faithfully recorded. At the upper end of the tonal scale, dynamic range is dictated by the point at which the RGB data "saturates" at values of 255, 255, 255. At the lower end of the tonal scale, dynamic range is determined by the point at which there ceases to be any useful difference between adjacent tonal steps. Note the use of the qualifier "useful" in there: While it's tempting to evaluate dynamic range as the maximum number of tonal steps that can be discerned at all, that measure of dynamic range has very little relevance to real-world photography. What we care about as photographers is how much detail we can pull out of the shadows before image noise becomes too objectionable. This, of course, is a very subjective matter, and will vary with the application and even the subject matter in question. (Noise will be much more visible in subjects with large areas of flat tints and subtle shading than it would in subjects with strong, highly contrasting surface texture.)

What makes most sense then, is to specify useful dynamic range in terms of the point at which image noise reaches some agreed-upon threshold. To this end, Imatest computes a number of different dynamic range measurements, based on a variety of image noise thresholds. The noise thresholds are specified in terms of f-stops of equivalent luminance variation in the final image file, and dynamic range is computed for noise thresholds of 1.0 (low image quality), 0.5 (medium image quality), 0.25 (medium-high image quality) and 0.1 (high image quality). For most photographers and most applications, the noise thresholds of 0.5 and 0.25 f-stops are probably the most relevant to the production of acceptable-quality finished images, but many noise-sensitive shooters will insist on the 0.1 f-stop limit for their most critical work. A full discussion of all the data Imatest produces is really beyond the scope of this review: Visit the Imatest website for details of what the program measures, how it performs its computations, and how to interpret its output.

JPEG. The graph at right (click for a larger version) was generated using Imatest's dynamic range analysis for an in-camera Panasonic GX1 JPEG file with a nominally-exposed density step target (Stouffer 4110). At default settings and base ISO of 160, the results show 10.5 f-stops of total dynamic range, with 7.07 f-stops at the "High" quality level. From the graph at top left, we can see gradation tapers-off fairly smoothly in both the highlight and shadow ends. These are pretty good results for a Micro Four Thirds sensor, but fall short compared to more recent APS-C sensors. Note, though, that this measurement has a margin of error of about 1/3 f-stop, so differences of less than 0.33 can be ignored when comparing results to other models.

RAW. The graph at right is from the same Stouffer 4110 stepchart image captured as a RAW (.RW2) file, processed with Adobe Camera Raw using the Auto setting. (Slightly better results are likely possible with manually tweaking, but we weren't able to do much better.) As can be seen, the score at the highest quality level was only slightly better than the in-camera JPEG, at 7.25 vs 7.07 f-stops, while total dynamic range only increased about 1/2 f-stop, to 10.9 versus 10.5 f-stops. Again, these results aren't bad for a Micro Four Thirds sensor, but they lag current APS-C sensors, especially at the High Quality threshold. It's worth noting here is that ACR's default noise reduction settings reduced overall noise somewhat (see the plot in the lower left-hand corner) relative to the levels in the in-camera JPEG, which would tend to boost the dynamic range numbers for the higher quality thresholds.

Contrast Adjustment
The camera's contrast adjustment was at least some help in handling the harsh lighting.

The Panasonic Lumix DMC-GX1's lowest contrast setting did a good job bringing out detail in the shadows and darker midtones, but it did little did little to preserve clipped highlight detail in the Sunlit Portrait shot. (The Far-field shot had few highlights clipped to begin with.) Overall, the camera's limited dynamic range makes it perform a bit below average in this situation.

The table above shows results with the default as well as the two "extreme" contrast settings. Click on any thumbnail above, then click again to see the full-sized image. The control for contrast was not quite as subtle as saturation was in its effect, though it appeared to leave the strongest highlights at about the same values, then applied a proportional boost to tones as it moved down the tone curve. To make the most of it in a shot like this, you'll want to expose for the highlights and apply a good amount of contrast reduction (probably the maximum).

The Panasonic GX1's contrast adjustment doesn't help with strong highlights here, and we'd really like to see more steps, covering a slightly greater range. Even with the lowest contrast setting, the dynamic range isn't terribly impressive.

Panasonic's Intelligent Dynamic Range
The above shots are examples of Panasonic's Intelligent Dynamic Range Control (or iD-Range) at work, with no exposure compensation. iD-Range appears to be a more advanced version of iExposure found on older models, capable of boosting shadows and preserving highlights, whereas iExposure worked mostly on shadows. Note that the camera does not take multiple shots and merge as some cameras' high dynamic range modes do. It's a system that adjusts local contrast and exposure more akin to Nikon's Active D-lighting, Canon's Automatic Lighting Optimization or Sony's Dynamic Range Optimization.

There are three levels of iD-Range available on the Panasonic GX1: Low, Standard and High, plus Off. It's automatically invoked in iAuto and some scene modes and manually selectable in PASM modes. For our Sunlit Portrait shot, all three settings were an improvement over the Off setting, lightening shadows and delivering a better exposure overall, while doing a very good job at holding on to highlight detail. (The histogram does a good job at showing how shadows were boosted while highlights were kept roughly the same.) However, noise is more visible in the shadows (as expected when boosting them), and the higher settings look a little unnatural, at least in these portrait shots. Still, iD-Range can provide a useful extension to the practical dynamic range of the Panasonic GX1. (It's not likely increasing the technically defined dynamic range of the sensor any, but it can make for much more usable/printable images when working under tough lighting conditions.)

Face Detection
Like most cameras these days, the Panasonic Lumix DMC-GX1 has the ability to detect faces (up to 15 in a scene), and adjust exposure and focus accordingly. The GX1 does it automatically in Intelligent Auto (iAuto) and iAuto Plus modes, when Portrait scene mode is selected, or when Face Detection AF mode is enabled. As you can see from the examples above, it made a difference in both iAuto and Portrait scene modes, though the camera selected different apertures and shutter speeds resulting in very different exposures. In both cases, the camera also automatically applied Intelligent D-range Correction as well (Standard level for iAuto, Low for Portrait).

Low Light. The Panasonic Lumix DMC-GX1 performed fairly well in our low light test, capturing bright images down to the lowest light level we test at, at all ISO settings. This darkest level equates to about 1/16 the brightness of average city street lighting at night, so the Panasonic GX1 should be able to take well-exposed photos in almost any environment in which you can see well enough to walk around in. The GX1's metering system struggled a bit at lower levels, as do many cameras, so these shots were taken in manual exposure mode. Automatic color balance was pretty good (just slightly cool), something that's not a given at such low light levels. Using default noise reduction setting, noise was low fairly up to ISO 800. At ISOs 1,600 and above, noise was a little higher at lower light levels compared to most recent cameras with APS-C sensors, but pretty good for a MFT model. Some minor horizontal banding was visible in the shadows at higher ISOs and lower light levels, but nothing unusual. We didn't see any issues with hot or stuck pixels, though when noise reduction is turned down and long shutter NR disabled at the lowest light level, there were quite a few red and blue speckles visible at ISO 200 and 400. There's also a hit of some very minor heat blooming in the bottom right-hand corner at very high ISOs, but again, that's not unusual.

The camera's autofocus system was able to focus on the subject down to below 1/16 foot-candle light level unassisted with an f/2.8 lens which is excellent, especially for a camera with contrast-detect autofocus. The Panasonic Lumix DMC-GX1 does have a focus-assist light option which allows it to autofocus in total darkness, as long as the subject is within range and has sufficient contrast.

How bright is this? The one foot-candle light level that this test begins at roughly corresponds to the brightness of typical city street-lighting at night. Cameras performing well at that level should be able to snap good-looking photos of street-lit scenes.

NOTE: This low light test is conducted with a stationary subject, and the camera mounted on a sturdy tripod. Most digital cameras will fail miserably when faced with a moving subject in dim lighting. (For example, a child's ballet recital or a holiday pageant in a gymnasium.) Thanks to their phase-detect AF systems, digital SLRs tend to do much better than point & shoots, but you still shouldn't expect a quick autofocus lock with moving subjects. The GX1 uses contrast-detect autofocus, as is found in most point & shoot cameras, so its low-light focusing ability is less than that of some SLRs with phase-detect systems. That said, though, the larger, more sensitive pixels of the GX1's sensor do better under dim lighting than do the tiny pixels of most point & shoots, (A useful trick is to just prop the camera on a convenient surface, and use its self-timer to release the shutter. This avoids any jiggling from your finger pressing the shutter button, and can work quite well when you don't have a tripod handy.)

Print Quality

ISO 160/200 shots look great at 20x30 inches; ISO 1,600 shots made good 11x14-inch prints; and we found good 5x7-inch prints from ISO 6,400.

ISO 160 shots look great printed at 20 x 30 inches, with nice color and detail.

ISO 200 shots are almost identical, being nearly the same exposure, so 20 x 30 inch prints look just fine.

ISO 400 images are a little softer at 20 x 30, if still usable; but they look better at 16 x 20, which is still quite large.

ISO 800 shots are not usable at 20 x 30, as low-contrast detail looks a bit too hazy. 16 x 20 inch prints look better, but are still just a bit hazy in a few areas.

ISO 1,600 images start to show a bit too much of a green cast in yellows, and noticeable noise in flatter areas, requiring a reduction to 11 x 14 inches.

ISO 3,200 images are usable for less critical applications at 11 x 14 inches, though the red leaf swatch in our Still Life image is a total blur, and yellows continue toward green. We have to prefer the image printed at 8 x 10.

ISO 6,400 image are too noisy at 8 x 10 inches, but look fairly good at 5 x 7.

ISO 12,800 images are a little flatter overall than the other settings and this ISO is best avoided for most applications.

Overall, the GX1 does quite well, with a large starting size of 20 x 30, easily maintaining good quality all the way down to 5 x 7 at ISO 6,400. Oddly, as ISO rises, at around 3,200 printed quality is not quite as high as we saw on the Panasonic G3, even when comparing the printed images side-by-side. It might have to do with a slightly different exposure at those settings.

Testing hundreds of digital cameras, we've found that you can only tell just so much about a camera's image quality by viewing its images on-screen. Ultimately, there's no substitute for printing a lot of images and examining them closely. For this reason, we now routinely print sample images from the cameras we test on our Canon Pro9000 Mark II studio printer, and on the Canon Pixma MP610 here in the office. (See the Canon Pixma Pro9000 Mark II review for details on that model.)